Polypyrrole Particles Research Articles

Structure-function relationship for functional films with constructed graded channels in dye/salt separation and fouling resistance

The structural assembly of polypyrrole particle stacking, combined with polydopamine space-filling, forms composite film with a network of interconnected fluid channels. The composite films achieve high water flus, separation efficiency and ratio of organic dyes/inorganic salts (flux: >600 L m−2 h−1 bar−1; dye rejection: ~100 %; salt rejection: <5 %). Simulation using different dye fouling models show that the dye only interacts at the surface, and hardly affects internal pores of the film throughout the filtration process. Owing to the patterned surface structure as constructed by microsphere arrangement and inter-structure adaptation assembly, the functional film has excellent contamination tolerance and rinsing regeneration for macromolecular pollutants. The results of computational fluid dynamics simulations further indicate that the high shear stress above the microspheres with vortex flow in the interstitial space has a positive effect on reducing contaminant deposition. In addition to the separation property, the composite film shows good structural stability and mechanical strength in various complex water environments, benefiting their future practical applications. This work unveils the structure-function relationship for composite function films with constructed graded channels in dye/salt separation, which is important for the design and future application of these functional films.

A Hydrogel-coated Wood Membrane with Intelligent Oil Pollution Detection for Emulsion Separation.

Considering the potential threats posed by oily wastewater to the ecosystem, it is urgently in demand to develop efficient, eco-friendly, and intelligent oil/water separation materials to enhance the safety of the water environment. Herein, an intelligent hydrogel-coated wood (PPT/PPy@DW) membrane with self-healing, self-cleaning, and oil pollution detection performances is fabricated for the controllable separation of oil-in-water (O/W) emulsions and water-in-oil (W/O) emulsions. The PPT/PPy@DW is prepared by loading polypyrrole (PPy) particles on the delignified wood (DW) membranes, further modifying the hydrogel layer as an oil-repellent barrier. The layered porous structure and selective wettability endow PPT/PPy@DW with great separation performance for various O/W emulsions (≥98.69% for separation efficiency and ≈1000Lm-2h-1bar-1 for permeance). Notably, the oil pollution degree of PPT/PPy@DW can be monitored in real-time based on the changed voltage generated during O/W emulsion separation, and the oil-polluted PPT/PPy@DW can be self-cleaned by soaking in water to recover its separation performance. The high affinity of PPT/PPy@DW for water makes it effective in trapping water from the mixed surfactant-stabilized W/O emulsions. The prepared eco-friendly and low-cost multifunctional hydrogel wood membrane shows promising potential in on-demand oil/water separation and provides new ideas for the functional improvement of new biomass oil/water separation membrane materials.

Polypyrrole-wool composite with electrical heating properties fabricated via layer-by-layer method

This study presents the development of conductive polymer-textile composites with outstanding electric heating properties achieved through the in-situ polymerization of polypyrrole on wool-felt fabrics, renowned for their superior thermal insulation. Employing successive layer-by-layer (LBL) cycles facilitated precise control over the uniform deposition of polypyrrole with the fabrics. The investigation focused on the interaction between wool fiber and polypyrrole, evaluating appearance, add-on, and electrical heating performance with varying LBL cycles. The polymerization process resulted in the formation of spherical polypyrrole particles on the wool-felt, with deposition increasing alongside LBL cycle numbers. Mechanical properties, including tensile strength and bending rigidity, exhibited enhancement with polypyrrole deposition, while strain reduction was noted, with minimal influence from LBL cycles. Electrical properties, particularly surface resistance, displayed a rapid decrease up to the second LBL cycle. Concerning electrical heating performance, the application of a 12 V voltage resulted in a linear increase in surface temperature with increasing LBL cycles, peaking at 15.5 ℃. Notably, this sustained electrical heating effect persisted even after voltage removal, attributed to the low thermal conductivity of wool fiber. Moreover, the polypyrrole conductive layer maintained exceptional conductivity following repeated abrasion and washing, credited to improved uniformity through LBL cycles. The synergy of wool's insulating properties and polypyrrole's conductivity, as confirmed in this study, presents the potential for a highly efficient heating fabric. These developed materials exhibited improved heating performance, energy conservation, and minimal change in mechanical properties, making them suitable for applications such as electrical heating smart clothing.

Vertical porous aerogel based on polypyrrole and bimetallic modified β-cyclodextrin polymer-chitosan for efficient solar evaporation

Solar-driven interfacial evaporation (SDIE) stands out as a prospective technology for freshwater production, playing a significant role in mitigating global water scarcity. Herein, a cyclodextrin polymer/chitosan composite aerogel (PPy-La/Al@CDP-CS) with vertically aligned channels was prepared as a solar evaporator for efficient solar steam generation. The vertically aligned pore structure, achieved through directional freezing assisted by liquid nitrogen, not only improves water transport during evaporation but also enhances light absorption through multiple reflections of sunlight within the pores. The polypyrrole particles sprayed on the surface of the aerogel acted as a light-absorbing layer, resulting in an impressive absorbance of 98.15 % under wetting conditions. The aerogel has an evaporation rate of 1.85 kg m−2 h−1 under 1 kW m−2 irradiation. Notably, the vertical pore structure of the aerogel allows it to exhibit excellent evaporation performance and salt resistance even in highly concentrated salt solutions. Furthermore, this aerogel is an excellent solar-driven interfacial evaporator for purifying seawater and fluoride-containing wastewater. This photothermal aerogel has the advantages of excellent performance, low cost, and environmental friendliness, and thus this work provides a new approach to the design and fabrication of solar photothermal materials for water treatment.

Phase‐Separated Polyzwitterionic Hydrogels with Tunable Sponge‐Like Structures for Stable Solar Steam Generation

AbstractSolar steam generation (SSG) through hydrogel‐based evaporators has shown great promise for freshwater production. However, developing hydrogel‐based evaporators with stable SSG performance in high‐salinity brines remains challenging. Herein, phase‐separated polyzwitterionic hydrogel‐based evaporators are presented with sponge‐like structures comprising interconnected pores for stable SSG performance, which are fabricated by photopolymerization of sulfobetaine methacrylate (SBMA) in water‐dimethyl sulfoxide (DMSO) mixed solvents. It is shown that driven by competitive adsorption, the structures of the resulting poly(sulfobetaine methacrylate) (PSBMA) hydrogels can be readily tuned by the volume ratio of DMSO to achieve phase separation. The optimized phase‐separated PSBMA hydrogels, combining the unique anti‐polyelectrolyte effects of polyzwitterionic hydrogels, demonstrate a rapid water transport capability in brines. After introducing photothermal polypyrrole particles on the surface of the phase‐separated PSBMA hydrogel evaporators, a stable water evaporation rate of ≈2.024 kg m−2 h−1 and high solar‐to‐vapor efficiency of ≈97.5% in a 3.5 wt.% brine are obtained under simulated solar light irradiation (1.0 kW m−2). Surprisingly, the evaporation rates remain stable even under high‐intensity solar irradiation (2.0 kW m−2). It is anticipated that the polyzwitterionic hydrogel evaporators with sponge‐like porous structures will contribute to developing SSG technology for high‐salinity seawater applications.

A broadband and strong microwave absorption of Ti3C2Tx MXene/PPy composites with a core-shell structure

In this work, the layered Ti3C2Tx MXene were coated with polypyrrole particles by an in-situ polymerization method, and their electromagnetic wave absorption performance were systematically studied. The MXene/PPy composites presented an excellent electromagnetic wave absorption performance, the strongest reflection loss can reach − 68 dB at 2.68 mm. Meanwhile, when the thickness is 2.26 mm, the effective absorption bandwidth can reach 6.56 GHz (from 11.44 to 18 GHz), covering the entire Ku band (12–18 GHz). The multiple reflections at the heterogeneous interface, and the synergistic effect between the layered MXene and the conductive polypyrrole network made a combined effect on the optimized absorption. The MXene/PPy composites with a strong electromagnetic wave absorption, wide effective absorption bandwidth and corrosion resistance have a great value in aircraft and vessel fields.

One-photon absorption enhanced nonlinear absorption and optical limiting of the electrospun polyvinylpyrrolidone via excitation energy and incorporation of polypyrrole particles

One-photon absorption enhanced nonlinear absorption and optical limiting of the electrospun polyvinylpyrrolidone via excitation energy and incorporation of polypyrrole particles

Influence of the type and concentration of oxidant on the photoacoustic response of polypyrrole nanoparticles for potential bioimaging applications

The photoacoustic response of polypyrrole particles was studied in relation to the type and amount of oxidant used for their synthesis by photoacoustic spectroscopy. At the same time, a detailed study of the molecular structure of these particles was performed using infrared and Raman spectroscopy. It was found that the particles prepared using superstoichiometric amounts of the oxidizer, nPy:nOxi = 1:3, in the case of FeCl3 and stochiometric nPy:nOxi = 1:1, in the case of (NH4)2S2O8 - showed the best photoacoustic output. At ratios nPy:nOxi oxidants equal to or less than 1:2 in the case of FeCl3, oligomers and polypyrrole with a longer kinetic chain length might be formed, whereas the higher oxidant content no longer affects the quality of the product. In the case of oxidation by (NH4)2S2O8, amounts of oxidant higher than 1:2 led to the formation of over-oxidized products. Although nanoparticles prepared at the stoichiometric ratios of both oxidizing agents were equivalent in terms of the molecular structure determined by the IR and Raman spectra, the particles prepared by (NH4)2S2O8 show a slightly stronger PA signal.

Polypyrrole film synthesis via solution plasma polymerization of liquid pyrrole

Herein, a polymerization method is presented for forming polypyrrole films from liquid pyrrole using a solution plasma process (SPP) by adjusting the operating voltage waveform. Negatively or positively biased bipolar square-wave pulses were applied to a tungsten wire to generate plasma, while a copper tape served as a ground electrode as well as the metallic substrate for polymer film deposition. Solution plasma induced by negatively or positively biased bipolar square-wave pulses was mainly generated in the negative or positive half cycle of the operating voltage, respectively. Pyrrole anions, well known as strong bases, were generated by the SPP using the negatively biased bipolar square-wave pulse, which increased the pH level of the SP-processed pyrrole solution. The polypyrrole films were deposited onto the Cu tape, which served as the anode, only under this operation condition. Thereafter, the polypyrrole film, with a thickness of 22 µm and consisting of overlapped polypyrrole particles, was synthesized for 2 h. The differences in the discharge characteristics of the solution plasma driven by negatively and positively biased bipolar square-wave pulses initiated the formation of different reactive species of the pyrrole monomer. Based on these results, a mechanism for polypyrrole film formation using the SPP is proposed.

Cyclodextrin-Functionalized Polypyrrole Particles for the Extraction of Aromatics from Water.

We describe the preparation of oil-in-water (o/w) colloidal particles with a polypyrrole (pPy) shell in which cyclodextrin has been incorporated at the oil-water interface via either physical adsorption or reaction with the pPy shell. The utility of these particles was assessed by the extraction of organic dyes from water. In all cases, we found that cyclodextrin incorporation significantly improved dye uptake, giving up to 78 ± 11% dye extraction in the case of a 100 ppm solution of 4-nitroaniline with a covalently incorporated cyclodextrin. We demonstrated the ability of our colloidal particles to extract nicotine-derived nitrosamine ketone (NNK), a potent carcinogen, from aqueous solution. By treating the solution containing 100 ppm NNK with our particles over 24 and 48 h, we found that NNK removal reached 65 ± 2 and 83 ± 1%, respectively. The uptake could be improved by re-treating a solution with additional freshly prepared particles, to achieve 95 ± 1% NNK extraction with a covalently incorporated cyclodextrin.

Controlling scaffold conductivity and pore size to direct myogenic cell alignment and differentiation.

Skeletal muscle's combination of three‐dimensional (3D) anisotropy and electrical excitability is critical for enabling normal movement. We previously developed a 3D aligned collagen scaffold incorporating conductive polypyrrole (PPy) particles to recapitulate these key muscle properties and showed that the scaffold facilitated enhanced myotube maturation compared with nonconductive controls. To further optimize this scaffold design, this work assessed the influence of conductive polymer incorporation and scaffold pore architecture on myogenic cell behavior. Conductive PPy and poly(3,4‐ethylenedioxythiophene) (PEDOT) particles were synthesized and mixed into a suspension of type I collagen and chondroitin sulfate prior to directional freeze‐drying to produce anisotropic scaffolds. Energy dispersive spectroscopy revealed homogenous distribution of conductive PEDOT particles throughout the scaffolds that resulted in a threefold increase in electrical conductivity while supporting similar myoblast metabolic activity compared to nonconductive scaffolds. Control of freezing temperature enabled fabrication of PEDOT‐doped scaffolds with a range of pore diameters from 98 to 238 μm. Myoblasts conformed to the anisotropic contact guidance cues independent of pore size to display longitudinal cytoskeletal alignment. The increased specific surface area of the smaller pore scaffolds helped rescue the initial decrease in myoblast metabolic activity observed in larger pore conductive scaffolds while also promoting modestly increased expression levels of the myogenic marker myosin heavy chain (MHC) and gene expression of myoblast determination protein (MyoD). However, cell infiltration to the center of the scaffolds was marginally reduced compared with larger pore variants. Together these data underscore the potential of aligned and PEDOT‐doped collagen scaffolds for promoting myogenic cell organization and differentiation.

New approach to prepare cytocompatible 3D scaffolds via the combination of sodium hyaluronate and colloidal particles of conductive polymers

Bio-inspired conductive scaffolds composed of sodium hyaluronate containing a colloidal dispersion of water-miscible polyaniline or polypyrrole particles (concentrations of 0.108, 0.054 and 0.036% w/w) were manufactured. For this purpose, either crosslinking with N-(3-dimethylaminopropyl-N-ethylcarbodiimide hydrochloride and N-hydroxysuccinimid or a freeze-thawing process in the presence of poly(vinylalcohol) was used. The scaffolds comprised interconnected pores with prevailing porosity values of ~ 30% and pore sizes enabling the accommodation of cells. A swelling capacity of 92–97% without any sign of disintegration was typical for all samples. The elasticity modulus depended on the composition of the scaffolds, with the highest value of ~ 50 kPa obtained for the sample containing the highest content of polypyrrole particles. The scaffolds did not possess cytotoxicity and allowed cell adhesion and growth on the surface. Using the in vivo-mimicking conditions in a bioreactor, cells were also able to grow into the structure of the scaffolds. The technique of scaffold preparation used here thus overcomes the limitations of conductive polymers (e.g. poor solubility in an aqueous environment, and limited miscibility with other hydrophilic polymer matrices) and moreover leads to the preparation of cytocompatible scaffolds with potentially cell-instructive properties, which may be of advantage in the healing of damaged electro-sensitive tissues.

Microfibers of polylactic acid with polypyrrole particles with ultrahydrophobic surface

Microfibers of polylactic acid with polypyrrole particles with ultrahydrophobic surface

Pyrrole-tailed imidazolium surface-active monomers: aggregation properties in aqueous solution and polymerization behavior

Pyrrole-functionalized imidazolium surfactants PyCnMImBr with different alkyl chain lengths (n = 8, 10, 12) were synthesized and their aggregation properties in water were investigated by tensiometry and conductimetry. These studies show that PyCnMImBr surfactants present lower critical micellar concentration than their non-functionalized analogues due to (i) an increased hydrophobicity resulting from the extension of the alkyl chain length upon incorporation of pyrrole (ii) the formation of attractive π-π interactions among pyrrole moieties. The areas occupied by PyCnMImBr molecules are always higher than those of CnMImBr surfactants showing looser molecular arrangement at the air-water interface due to steric hindrance of pyrrole moieties. 1H nuclear magnetic resonance measurements have been used to shed light on the structure of the aggregates formed. In all cases, pyrrole is located inside the micellar core but for the shortest alkyl chain length, it tends to intercalate between the alkyl chains. Micelles obtained with PyC12MImBr were further used as nano-reactor to prepare water-stable polypyrrole nanoparticles. For this, we conduct the chemical polymerization of pyrrole inside the micelles using FeCl3 as oxidizing agent. Polymerization kinetics were followed by UV-spectroscopy. Combined with Infrared (IR) and Dynamic Light Scattering (DLS) measurements, we confirmed the formation of polypyrrole particles of about 4 nm that were water-stable thanks to the presence of cationic imidazolium functions on their surface.

Relationships between polypyrrole synthesis conditions, its morphology and electronic structure with supercapacitor properties measured in electrolytes with different ions and pH values

Despite a large number of articles about synthesis methods, structure, morphology and electrochemical properties of polypyrrole, none of these works reports the relationships between polypyrrole synthetic conditions, the electronic states of atoms in the polymer chains and its electrochemical properties in various electrolytes. Our work is dedicated to filling part of this gap. This work is focused on the effect of the synthetic medium used for polypyrrole synthesis on their atomic and electronic structure and morphology as well as investigation of the influence of these on the electrochemical characteristics of polypyrrole in aqueous electrolytes with different ions and pH values within a supercapacitor setup. It is shown that synthetic medium does not affect polymer particle shapes but changes particle sizes. Using oxygen functional groups containing synthetic medium based on water and ethanol leads to a decrease in C:N ratio, increase in C:O ratio, increase in the concentration of positively charged nitrogen-species and formation of linear-structured polymer chains. Contrary, acetonitrile-based synthetic medium without oxygen-containing functional groups leads to an increase in C:N ratio and concentration of neutrally charged nitrogen species, decrease in C:O ratio and formation of branched-structured polymer chains. Electrochemical properties of polypyrrole depend on the nature of the electrolyte, then nitrogen species and oxygen-containing functional groups in polypyrrole structure, and the size of polypyrrole particles. The favorable electrolyte for using polypyrrole in supercapacitors is neutral. The specific capacitance of polypyrrole produced in acetonitrile is shown to reach the value of ~ 385 F g −1 which is stable for more than 10,000 cycles in 1M KCl aqueous solution.

Ti3C2-MXene composite films functionalized with polypyrrole and ionic liquid-based microemulsion particles for supercapacitor applications

Stemming from its unique structure and properties, Ti3C2-MXenes have stood out from the crowd of electrode materials due to effectively ameliorating imperfections of common ones for excellent energy storage. However, a major stumbling block in the further development of MXene-based supercapacitors is the inherent low capacities caused by severe restacking of nanosheets. Herein, we develop a simple, effective and innovative strategy, namely, introducing both polymerized polypyrrole (PPy) particles and ionic liquid (ILs)-based microemulsion particles as “dual spacers”, to fabricate functionalized Ti3C2-MXene composite films for high-performance and wide-temperature application in supercapacitors. The PPy particles acting as one “spacer” circumvent restacking issues of MXene nanosheets, while contribute to desirable capacitance of the hybrid material. ILs-based microemulsions spontaneously adsorbing onto PPy-Ti3C2Tx nanosheets are conceived to be one more liquid “spacer” for fast ion diffusion kinetics and absent electrolyte imbibition steps, which is rarely reported in previous research for MXene-based electrode materials. These features endow the composite films with excellent specific capacitance, rate capability and cycling stability between 4 °C and 50 °C. At room temperature, the symmetric supercapacitor device based on the composite films delivers a maximum gravimetric energy density of 31.2 Wh kg−1 (at 1030.4 W kg−1) and reserves 91% of the initial specific capacitance with a coulombic efficiency of 91% after 2000 cycles. All these impressive results substantiate that the composite films prepared by ingenious structure design showcase huge potentials in advanced MXene-based supercapacitors using various ionic liquid electrolytes.

Polypyrrole-Doped Conductive Self-Healing Composite Hydrogels with High Toughness and Stretchability.

In recent years, hydrogels with self-healing capability and conductivity have become ideal materials for the design of electrodes, soft robotics, electronic skin, and flexible wearable devices. However, it is still a critical challenge to achieve the synergistic characteristics of high conductivity, excellent self-healing efficiency without any stimulations, and decent mechanical properties. Herein, we developed a ferric-ion (Fe3+) crosslinked acrylic acid and chitosan polymer hydrogel using embedded polypyrrole particles with features of high conductivity (2.61S·m-1) and good mechanical performances (a tensile strength of 628%, a stress of 0.33 MPa, an elastic modulus of 0.146 MPa, and a toughness of 1.14 MJ·m-3). In addition, the self-healing efficiency achieved 93% in tensile strength after healing in the air for 9 h without any external stimuli. Therefore, with these outstanding mechanical, self-healing, and conductive abilities all in one, it is possible to fabricate a new kind of soft material with wide applications.

Fabrication and characterization of conductive polypyrrole/chitosan/collagen electrospun nanofiber scaffold for tissue engineering application

Conductive electrospun nanofiber scaffold containing conductive polypyrrole (PPy) polymer was fabricated to accelerate healing of damaged tissues. In order to prepare these scaffolds, various weight percentages of polypyrrole (5, 10, 15, 20, 25%) relative to the polymers combination (chitosan, collagen, and polyethylene oxide) were used. The fabricated composite scaffolds were characterized using chemical, morphological, physio-mechanical, and biological analyses including; FTIR spectroscopy, SEM, electrical conductivity, tensile test, in vitro degradation, MTT Assay and cell culture. The polypyrrole particles were perfectly dispersed inside the nanofibers, and the fibers average diameter were reducing by increasing the polypyrrole content in the composites. The presence of polypyrrole in fibers enhanced their conductivity up to 164.274 × 10−3 s/m which is in the range of semi-conductive and conductive polymers. MTT and SEM analyses displayed that nanofibers composing 10% polypyrrole possess better cell adhesion, growth and proliferation properties comparing to other compositions. Furthermore, the suitable mechanical properties of scaffolds ideally fitted them for different kinds of tissue applications including skin, nerve, heart muscle, etc. Therefore, these fabricated conductive nanofiber scaffolds are particularly appropriate for employing in body parts with electrical signals such as cardiovascular, heart muscles, or nerves.

Structural, Electrical and Thermal Properties of Composites Based on Conducting Polymer

Abstract: In this work, we report the structural, thermal and electrical properties of composites consisting of polypyrrole particles in a polymethylmethacrylate matrix. Electrical resistivity analysis of these percolating composites showed a remarkable change in the conduction mechanisms below and above the percolation threshold. Structural properties were studied using X-ray diffraction, showing increases in the crystallinity index for filler concentrations above the critical percolation. Thermogravimetric analysis was used to study thermal degradation. It shows a transition from a single peak for concentrations below the percolation threshold to a double peak for concentrations above that point. The increase in the degradation temperature with the concentration of polypyrrole indicates the increase of thermal stability. Keywords: Conducting polymer, Percolation threshold, Crystallinity, Thermal degradation, X-Ray diffraction.

Ethylene-Octene-Copolymer with Embedded Carbon and Organic Conductive Nanostructures for Thermoelectric Applications.

Hybrid thermoelectric composites consisting of organic ethylene-octene-copolymer matrices (EOC) and embedded inorganic pristine and functionalized multiwalled carbon nanotubes, carbon nanofibers or organic polyaniline and polypyrrole particles were used to form conductive nanostructures with thermoelectric properties, which at the same time had sufficient strength, elasticity, and stability. Oxygen doping of carbon nanotubes increased the concentration of carboxyl and C–O functional groups on the nanotube surfaces and enhanced the thermoelectric power of the respective composites by up to 150%. A thermocouple assembled from EOC composites generated electric current by heat supplied with a mere short touch of the finger. A practical application of this thermocouple was provided by a self-powered vapor sensor, for operation of which an electric current in the range of microvolts sufficed, and was readily induced by (waste) heat. The heat-induced energy ensured the functioning of this novel sensor device, which converted chemical signals elicited by the presence of heptane vapors to the electrical domain through the resistance changes of the comprising EOC composites.